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Bushfire smoke plume destined to reach Australia again after circling the globe, NASA says

By Daniel Keane, Monday January 13, 2020 - 20:56 EDT
ABC licensed image
Sydney was blanketed in bushfire smoke in December. - ABC licensed

NASA is predicting smoke from the country's devastating bushfires will make it all the way around the world, with the potential to move over Australian skies again in the coming days.

However, one expert has said it may not be visible to the naked eye.

Several Australian cities have already been blanketed with smoke during the bushfire crisis in the past few weeks, including Canberra, Adelaide, Melbourne and Sydney, .

Satellite imaging tracking the progress of a smoke plume shows it drifting out over the Tasman Sea and then to the Pacific Ocean.

"Over the past week, NASA satellites have observed an extraordinary amount of smoke injected into the atmosphere from the Australian fires and its subsequent eastward dispersal," the agency said on its website.

"The smoke is expected to make at least one full circuit around the globe, returning once again to the skies over Australia."

NASA has been monitoring the movement of smoke from the Australian bushfires for at least the past fortnight, .

"The smoke is having a dramatic impact on New Zealand, causing severe air quality issues across the country and visibly darkening mountain-top snow," the agency said.

NASA said the intense heat from bushfires across Australia — including New South Wales, Victoria, the Adelaide Hills and Kangaroo Island — had triggered fire-induced thunderstorms.

University of New South Wales astrophysicist Lisa Harvey-Smith has been following the plume's progress through NASA images.

She said it would not be long before the smoke was travelling in Australian airspace again.

"I would expect the smoke to have completely circled the globe and be visible above southern parts of WA in the next few days, probably not at ground level but high in the atmosphere," Professor Harvey-Smith said.

Smoke particles could do 'several loops'

Professor Harvey-Smith said the smoke cloud had "already enveloped around three quarters of the world" and was being pushed along by thunderstorms generated by the fires, and had reached 17 kilometres above sea level.

"Being at that high altitude allows the smoke to travel relatively unimpeded, above most of the atmosphere and weather," she said.

ABC News Breakfast weather presenter Nate Byrne said the smoke would likely become diluted as it crossed over South America, meaning the plume may not be visible once it reaches Australia again.

"The old thinking was that the solution to pollution was dilution," he said.

"But in the case of these fires — they are so huge, they are still burning, and will be burning for quite some time — there's a constant of supply of smoke particles into the air.

"By the time the wind gets all the way back around to the west of Australia, it's spent a lot of time being mixed with clean air from higher up or lower down in the atmosphere, so you won't see the thick smoke like you'd see right next to the fire.

"Most likely the only way we'll be able to detect it is from satellites."

However, Byrne said it was still possible that Perth locals might notice a "hazy day" soon.

He said while it did not appear to have reached the west coast just yet, it probably would "within days".

"Smoke particles don't disappear — they have to be removed from the air somehow," he said.

"The more smoke particles there are in the air, the more likely it is that some will be able to make it all the way around the Earth and, in fact, maybe do several loops.

"Just like when you see really huge volcanic explosions, the ash from those can travel several times around the globe and cause havoc for quite some time."



© ABC 2020

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